It is well known that in order to meet achieve low price and high supply demands for semiconductor devices, semiconductor manufacturers have developed semiconductor wafer processing techniques and methods which are oriented toward batch processing. Batch processing techniques usually involve the temporary storage and transportation of a plurality of semiconductor wafers from one processing station to another in the manufacturing facility. This is almost universally accomplished by employing plastic semiconductor wafer cassettes which typically hold twenty-five semiconductor wafers.
In the ordinary course of handling and processing the semiconductor wafers, it is necessary to inscribed or otherwise mark each semiconductor wafer with indicia which provides important processing information. Such information typically pertains to the plant number where the semiconductor wafer is being processed, the lot number to which the semiconductor wafer belongs, the number of the semiconductor wafer and other like information in order to enables the proper processing and production routing of the wafers.
During the processing of semiconductor wafers it is often desirable to select a specific one or more wafers from the wafer cassette for various reasons such as quality control audits and the like. This requires the ability to visually read the identification indicia located on each of the wafers in the cassette at the same time so that the desired wafer can be located and removed from the cassette. Presently, this is only possible by individually removing each wafer one at a time and reading its identifying indica and then loading the wafer back into the cassette until the desired wafer is located which is extremely time consuming and involves considerable risk of wafer contamination and breakage.
Accordingly, there is a need for an apparatus which avoids the need for individually removing each wafer one at a time in order to visually read the identification indicia located on the wafer.